Alloy 309/309S (UNS S30900/S30908) austenitic stainless steel is typically used for elevated temperature applications. Its high chromium and nickel content provides comparable corrosion resistance, superior resistance to oxidation, and the retention of a larger fraction of room temperature strength than the common austenitic Alloy 304.

ASTM 309S stainless steel plate is often used for high temperature applications. AISI 309S stainless steel sheet has a much less carbon composition, which minimizes carbide precipitation, and improves weldability.AISI 309S (S30908)steel sheet is typically used for elevated temperature applications.